The amount of data on skeletal muscle metabolism published during the last 15 years contrasts with the lack of information on smooth muscle metabolism over this same period. We have been studying the intermediary metabolism of nonhuman primate myometrium (Macaca mulatta and Macaca fascicularis) during pregnancy and during the follicular and luteal phases of an induced and a natural menstrual cycle. The overall goal of our tudies is to gain information on metabolic control mechanisms in this smooth muscle: inter-relationships of carbohydrate, lipid and protein metabolism, and cyclic nucleotide metabolism. Recently we have been able to collect, quick-freeze, and store (minus 200 degrees C) myometrial samples from about 30 naturally cycling macaque monkeys and 30 monkeys spayed for at least 6 months and treated with estradioal-17 beta (E2) for 14 days, or with E2 for 14 days and then for 5 to 14 additional days with E2 plus progesterone (P). Plasma levels of E2 and P were determined at the time of biopsy (radioimmunoassay) and were paired in the spayed monkeys treated with hormones and the naturally cycling monkeys. The activity of the enzymes synthesizing and degrading the cyclic nucleotides will be determined in myometrial samples from these monkeys. Preliminary work indicates that guanylate cyclase is less active in luteal than in follicular myometrium, and adenylate cyclase is more active. We also intend to measure the levels of prostaglandins E2 and F2 alpha, and the activity of the cAMP- and cGMP-dependent protein kinases in myometrium during the follicular and luteal phase of the menstrual cycle. The total activity and kinetics of the rate-limiting enzymes, hexokinase types I and II will be studied in these myometrial samples and the sensitivity of these enzymes to various effector molecules such as ADP and citrate. Levels of enzyme activity will also be measured in samples of taenia coli to determine if the changes seen during the menstrual cycle are specific for myometrial smooth muscle.